Are 2-1/2 inch Pipes Stock?

[boboh1]

I am looking to replace my mufflers but am wondering what size pipes I have. Everything is welded so cannot measure inside diameter. Have a 69 Bee with 383 and the stock exhaust manifolds. Would it probably be 2-1/2 inch pipes?

 

[AR67GTX]

I think 383 Roadrunner and Super Bee head pipes were 2-1/4” and tailpipes 2-1/4” all stock. The 440 and Hemi cars got 2-1/2” head pipes and 2-1/4” tailpipes. But, do you have a stock system on it now?

 

[boboh1]

That’s a good question. I got the car not too long ago and not exactly sure what the previous owner installed. The mufflers have no manufacture markings visible from what I can see. The mufflers I am looking at have a 2-1/2 inlet and outlet.

 

[33 IMP]

That’s a good question. I got the car not too long ago and not exactly sure what the previous owner installed. The mufflers have no manufacture markings visible from what I can see. The mufflers I am looking at have a 2-1/2 inlet and outlet.

You can find what you have now, both head and tailpipes, using the string trick. Wrap a string around the pipe, and mark it. Measure the length, and divide by pi, 3.14.
Around 7" for 2 1/4, almost 8" for 2 1/2.
(Interesting note: 3"tubing has around 40% more area than a 2 1/2 tube.)

 

[33 IMP]

@dadsbee would certainly know stock pipe diameters for a superbee 383...... but how do you know you have a stock system on a 55 year old car?
(My 440 rr is indeed, 2 1/2 headpipe, 2 1/4 tailpipe. Still has 1969 tubing on it)

 

[boboh1]

You can find what you have now, both head and tailpipes, using the string trick. Wrap a string around the pipe, and mark it. Measure the length, and divide by pi, 3.14.
Around 7" for 2 1/4, almost 8" for 2 1/2

That’s brilliant. I’ll do the measuring and math. Thanks.

 

[33 IMP]

That’s brilliant. I’ll do the measuring and math. Thanks.

Welcome. Happy to help fellow Claremonter.

 

[dadsbee]

ECS actually used my original headpipes to make their jig and produce 383 OE correct exhaust systems in 2015.

That said if yours are welded up who knows if theyr're OE? Mufflers... 383 AND 440 are 2 1/4" in and out, despite what the pipe diameter is.

 

[Dave6T4]

You could upgrade your Super Bee to 2 1/2" head pipes for better breathing. The HP exhaust manifolds are designed for it. This was a little trick we did back in the day; swap our Super Bee exhaust for larger R/ T pieces. No one was the wiser. If some one is under your car, measuring your exhaust at a car show, they are just too close!

 

[dadsbee]

Stock mufflers are still 2.25 in and out..

 

[33 IMP]

Stock mufflers are still 2.25 in and out..

Will a 2 1/2 muffler fit OVER 2 1/4 tubing, without having to be welded?

 

[dadsbee]

Will a 2 1/2 muffler fit OVER 2 1/4 tubing, without having to be welded?

I'm handicapped.. at camp and all my exhaust pics are on desk top. Headpipes are squashed to fit the mufflers.

 

[lewtot184]

383 and 440 came with same manifolds. 383 had a 2.25 head pipe swaged up for the larger exhaust manifold exit. Anyhow a 2.5 inch head pipe and exhaust will fit.

 

[AR67GTX]

I believe that’s correct that 440/426 mufflers were still 2.25” in and out stock. But if cost is not an issue, from Accurate Exhaust you can get a factory appearing 2.5” head pipe and 2.5” in and 2.25” out Hemi mufflers as an option.

Not sure if the larger muffler entrance really frees up any horsepower or not as exhaust gasses should already be cooling down by the time they hit the muffler entrance. The 2-1/2” head pipes should be worth something on a healthy 383.

 

[sam dupont]

On a tight budget? Make offer. (not mine)

 

[AR67GTX]

Those could be Accurate mufflers, not sure. If so that’s about 1/3 their list price.

Edit: No, I don’t think they are. I don’t see the corner bead crimps. Still might be a good buy.

 

[Fran Blacker]

On a tight budget? Make offer. (not mine)

View attachment 1682827

If you look at description down lower it's 2.25" in and out

 

[33 IMP]

@boboh1, check out Jones Exhaust on summits site. Stainless mufflers for a good price. I'm guessing summits profit margin on them is razor thin, since they do nothing to promote them. You'll have to go in the exhaust section, and specify Jones exhaust as the brand, otherwise you won't find them.

 

[boboh1]

I checked my diameters. Shout out to 33 IMP who got an A in math class. Pipe before the muffler is 2.31. After 2.1 and the muffler out/inlet is 2.4 inches. Guess that it why the outlet is welded.

 

[boboh1]

I’ll check out Jones exhaust. Not sure how they sound. I am thinking of Flowmaster 50 Delta Flow